<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>

<body>
    <!-- Create a simple CodeMirror instance -->
    <link rel="stylesheet" href="codemirror.css">
    <script src="codemirror.js"></script>
    <script>
        var myTextarea = document.createElement("textarea")

        document.body.appendChild(myTextarea)
        var editor = CodeMirror.fromTextArea(myTextarea, {
            lineNumbers: true
        });
    </script>
</body>

</html>